Modified epoxy resins and process for producing same

Abstract

Modified cationic epoxy resins wherein phenols linked through modified urea groups are used to extend the chain of diepoxy resins are described. The modified cationic resins can be formulated as paints which exhibit excellent properties particularly when used for electrodeposition paints.

It is claimed: 
     
       1. Process for producing cationic epoxy resins modified through chain prolongation, characterized in that a reaction product (A1) of two moles of an aminoalkylation product, carrying one NH-group, obtained through reaction of a phenol carrying at least one formaldehyde-reactive site, with a primary amine and formaldehyde and one mole of a diisocyanate, or a reaction product     (A2) of one mole of a substituted urea obtained from one mole of a diisocyanate compound and two moles of a primary amine, two moles of formaldehyde, and two moles of a phenol having at least one formaldehyde-reactive site is reacted with     (B) one mole per phenolic hydroxy group of a diepoxy compound through etherification of the phenolic hydroxy groups, and   (C) the remaining epoxy groups are reacted with amine compounds or carboxy compounds whereby the final product carries basic nitrogen groups in a quantity corresponding to an amine value of from 35 to 150 mg KOH/g.   
     
     
       2. Process according to claim 1 further characterized in that a primary-tertiary diamine is used as the primary amine in the preparation of reaction products (A1) and (A2). 
     
     
       3. Process according to claim 1 further characterized in that the reaction of the amines or carboxy compounds is carried out simultaneously with, or after, the reaction of the epoxy compounds with reaction products (A1) or (A2). 
     
     
       4. Process according to claim 2 further characterized in that the reaction of the amines or carboxy compounds in step (C) is carried out simultaneously with, or after, the reaction of the epoxy compounds with reaction products (A1) or (A2). 
     
     
       5. Process according to claim 3 further characterized in that a carboxy compound which is a semiester of a dicarboxylic acid with hydroxy(meth)acrylates is utilized in step (C). 
     
     
       6. Process according to claim 4 further characterized in that a carboxy compound which is a semiester of a dicarboxylic acid with hydroxy(meth)acrylates is utilized in step (C). 
     
     
       7. Use of the products produced according to claim 1 as binders in stoving paints. 
     
     
       8. Use of the products produced according to claim 1 as binders in cathodically depositable electrodeposition paints. 
     
     
       9. Cationic epoxy resin comprising the reaction product of a diepoxy resin with (A1) a reaction product of two moles of an aminoalkylation product, carrying one NH-group, obtained through the reaction of a phenol carrying at least one formaldehyde-reactive site, with a primary amine and formaldehyde and one mole of a diisocyanate, or     (A2) reaction products of one mole of a substituted urea obtained from one mole of a diisocyanate compound and two moles of a primary amine, two moles of formaldehyde, and two moles of a phenol having at least one formaldehyde-reactive site, the ratio of diepoxy resin to reaction product (A1) or (A2) being on the basis of one mole of the diepoxy resin per phenolic hydroxy group on the reaction product of (A1) or (A2).     
     
     
       10. The cationic epoxy resin of claim 9 wherein the reaction product is further reacted with an amine compound or carboxy compound to provide an epoxy resin substantially free of epoxy groups, with the resin carrying basic nitrogen groups in a quantity corresponding to an amine value of from 35 to 150 mg KOH/g. 
     
     
       11. The cationic epoxy resin of claim 10 wherein the primary amine of (A1) and (A2) is a primary-tertiary diamine.